Recoil mehanism for machine guns with a hydraulic counter-recoil brake

ABSTRACT

A recoil-mechanism for machine guns with a hydraulic counterrecoil brake, wherein the recoil energy for effecting the weapon advance is stored and with a hydraulic braking piston equipped with throttle valves, which comprises a cylinder connected with reciprocating parts of the weapon and receiving a hydraulic braking piston. A housing has the cylinder disposed therein for longitudinal displacement and receiving the recoil-mechanism, and is connected with immovable parts of the weapon and supported on both sides by resilient abutments. Additional abutment means are effective upon the braking piston. The abutment means set the piston forwardly during the return stroke of the cylinder relatively to the latter, such, that the piston rod, formed as a ram and extending out from the end wall of the cylinder, is supportable during the forward stroke of the forward resilient abutment, before the cylinder itself has reached its initial position.

United States atent Harbrecht et al.

[1 1 3,668,969 [4 June 13, 1972 [54] RECOIL MEHANISM FOR MACHINE GUNS WITH A HYDRAULIC COUNTER- RECOIL BRAKE [72] Inventors: Karl Harbrecht, Eisental B, Bruhl; Gerhard Munn, Dusseldorf, both of Germany [73] Assignee: Rheinmetall Gmbl-l, Dusseldorf, Germany [22] Filed: March 6, 1970 [21] Appl. No.: 17,231

l-lerlach Primary xaminerBenjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorney-Ernest G. Montague ABSTRACT A recoil-mechanism for machine guns with a hydraulic counter-recoil brake, wherein the recoil energy for efiecting the weapon advance is stored and with a hydraulic braking piston equipped with throttle valves, which comprises a cylinder connected with reciprocating parts of the weapon and receiving a hydraulic braking piston. A housing has the cylinder disposed therein for longitudinal displacement and receiving the recoil-mechanism, and is connected with immovable parts of the weapon and supported on both sides by resilient abutments. Additional abutment means are effective upon the braking piston. The abutment means set the piston forwardly during the return stroke of the cylinder relatively to the latter, such, that the piston rod, formed as a ram and extending out from the end wall of the cylinder, is supportable during the forward stroke of the forward resilient abutment, before the cylinder itself has reached its initial position.

5 Claims, 2 Drawing Figures RECOIL MEI-IANISM FOR MACHINE GUNS WITH A HYDRAULIC COUNTER-RECOIL BRAKE The present invention relates to a recoil-mechanism for machine guns with a hydraulic counter-recoil brake, in which the recoil energy is stored for causing the counter-recoil of the weapon and is provided with a hydraulic brake-piston equipped with throttle valves, which brake-piston is arranged in a cylinder connected with the advancing and returning parts of the weapon.

Recoil-mechanisms with hydraulic counter-recoil brakes for guns are known in many designs, among them such, in which the braking 'force is influenced by a flow adjustment dependent upon the path. In such braking force control, dependent upon the path, very different braking forces occur, if due to unequally long weapon recoil and counter-recoils the speeds are different in dependency of the paths and/or if for reasons of the function of the weapon, as it is the case in recoilmechanisms for floatingly mounted machine guns, the full braking force is to be effective only during the last half of the recoil-path. The braking force should not surpass thereby at any point of the recoil-path, the force of the recoil-spring, in order that no, or only neglcctable, forces are transmitted forwardly to the cradle, as it occurs often in a burst of fire. On the other hand, a certain minimum-brake force is required, in order to rule a large cadence stray range of the weapon.

It is one object of the present invention, to provide a recoilmechanism for machine guns with a hydraulic counter-recoil brake, wherein independently from differently long counterrecoil paths and different speeds, the occurring braking force does not surpass a preset braking force.

It is another object of the present invention, to provide a recoil-mechanism for machine guns with a hydraulic counterrecoil brake, wherein the cylinder is disposed longitudinally displaceable in a housing receiving the recoil-mechanism and connected with the immovable parts of the weapon and is supported on both sides by resilient abutments, and wherein further supporting means effecting the brake piston are provided, which set the piston forwardly during the return stroke of the cylinder relative to the piston. This is brought about such, that the piston rod formed as a ram and emerging from the forward cylinder end wall is supportable during the forward stroke by the forward resilient abutment, before the cylinder itself reaches its initial position. The forward resilient abutment supported by the gun carriage is thereby pretensioned according to the preset braking force. Since the forward piston rod advanced during the return stroke is supported during its forward stroke on the resilient abutment, an occurring high point of the braking force can be absorbed effectively in this manner.

Advantageously the brake piston is equipped, in known manner, on both sides with a piston rod, which are mounted in end walls of the cylinder, which has the advantage that no particular balance chambers are required for the cross-section of the piston rods.

For the advancement of the piston during the return stroke of the weapon, either a spring can be provided between the piston and the rear end wall of the cylinder, or also the rear piston rod can be supported by a rigid abutment disposed in the housing or the recoil-mechanism.

It is still another object of the present invention to provide a recoil-mechanism for machine guns with a hydraulic counterrecoil brake, wherein the forward resilient abutment comprises two shoulder bushings disposed on a common holder with a spring disposed under tension between the shoulder bushings and is insertable as a structural element into the housing of the recoil-mechanism. By this arrangement the mounting of the recoil-mechanism is appreciably simplified, whereby additionally the pretension force of the abutment can be varied and set thereby in a simple manner such, that the joint holder comprises a screw bolt, which is releasable and adjustably secured in the forward shoulder bushing and is guided for longitudinal displacement in the forward shoulder bushing.

With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompaning drawing, in which:

FIG. 1 is a longitudinal section through the recoilmechanism with a force controlled brake piston; and

FIG. 2 is a fragmentary longitudinal section of another embodiment of the present invention with a spring-controlled brake piston.

Referring now to the drawing, the recoil-mechanism comprises a tubular housing 1 with a bottom 2 disposed at its rear end, in which the entire recoil-mechanism including the counter-recoil brake is disposed. Two such recoil-mechanisms are inserted releasably at both sides of the weapon 3 into the gun carriage (not shown), which is mounted relative to the weapon for the return movement. A hydraulic braking cylinder 4 is disposed in the housing for longitudinal displacement. The braking cylinder 4 has at its periphery a cam 5, which projects through a slot provided in the housing wall and which engages a recess 6 of the weapon. The braking cylinder has a rear end wall 7, while its front end wall forms a bushing 8 which can be screwed in. In the braking cylinder 4, which is filled with a braking fluid, is disposed a braking piston 9, which is equipped with piston rods 10 and 11, respectively, which piston rods are formed as rams, which are guided in the end walls of the braking cylinder 4. The piston 9 has a plurality of passage bores 12, as well as a return flow bore 13. The bores 12 fonn, together with a ring 14, as well as with a spring 15, supporting itself on the piston rod, a return valve.

In the position shown in FIG. 1, the resting position of the weapon, the rear piston rod 11 extends out of the cylinder 4 and is limited in its possible movement in rearward direction by a rigid abutment 16. The abutment 16, consisting substantially of a tube member, engages with a plate 17 at the bottom 2 of the housing 1 and is retained by a helical pressure spring 18 forming a recuperator spring, which helical pressure spring 18 is disposed under tension between the rear cylinder end wall 7 and the plate 17 and the bottom 2 of the housing 1, respectively.

The forward end wall 8 of the braking cylinder 4, as well as the forward piston rod 10 of the brake piston are supported by a resilient abutment 19 inserted in the forward part of the housing 1. This abutment 19 forms an independent structural element and comprises two shoulder bushings 20 and 21, which are disposed on a screw bolt 22 as a joint holder. The outer shoulder bushing 21 is rigidly inserted into the housing 1 and is retained by a screw cap 23. The screw bolt 22 is guided in this shoulder bushing 21 for longitudinal displacement, and is screwed into the inner shoulder bushing 20 with its threaded part and retained therein. A spring set 24 consisting of cup springs is disposed under tension between the shoulder bushings 21 and 22, which spring set 24 can be pretensioned to a predetermined spring force by turning the screw bolt 22. The inner shoulder bushing 20 is guided in this manner against the pretensioning force of the spring set 24 for longitudinal displacement in the housing 1.

The operation of the described the following manner:

During the return stroke of the weapon, the braking cylinder 4, which is coupled with the weapon by means of its cam 5, is displaced in the housing 1 against the force of the helical pressure spring 18. Since the rear piston rod 11 is supported by the rigid abutment 16, the return valve l2, l4 and 15 opens, whereby the brake fluid moves from the forward side of the piston to the rearward side. If the return flow path is terminated, the piston rod 10 extends out of the end wall 8 of the cylinder for the stroke of the weapon return and the valve spring 15 closes the return valve 14. The return stroke energy stored during the return flow path in the helical pressure spring 18 causes the forward movement of the weapon by means of the cam 5. Since the piston rod lo'extending out of the forward end wall of the cylinder and formed as a ram, finds mechanism is performed in its support on the resilient abutment 19 and the return valve 14 is closed, the brake fluid is pressed through the return flow bore 13 from the rearward cylinder chamber into the forward cylinder chamber. By this arrangement a pressure difference is created between the forward and rearward piston plane, so that the piston presses with a force (brake force) formed by the pressure difference times the piston plane onto the resilient abutment 19. If this force becomes greater than the pretensioned force of the abutment 19, a varied relative movement is created between the weapon and the piston, which relative movement reduces the pressure difference at the piston faces and thus the maximum braking force at the level of the pretension of the spring or, if the weapon forward speed is sufficiently reduced, becomes smaller than the pretension of the spring.

While the embodiment disclosed in FIG. 1 has a force-controlled brake piston, the embodiment disclosed in FIG. 2 is equipped with a spring-controlled brake piston, in which instead of providing the rigid abutment 16 (FIG. 1), a helical pressure spring 25, disposed between the brake piston 9 and the rear end wall 7 of the cylinder is provided, in order to advance the brake piston. In this embodiment, the brake piston 9 is advanced by the spring 25 during the return stroke of the weapon, by engaging the brake piston 9 at the forward end wall 8 of the cylinder, prior to the termination of the return stroke. Since thereby the return valve is closed in the piston, the end of the return stroke is braked. During the forward run, this returned valve is still open, so that the advancement starts without braking, until the ram 10 hits the pretensioned spring abutment l9, whereupon the further advance of the weapon is barked in the manner described in FIG. 1.

While we have disclosed two embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense.

We claim:

1. A recoil-mechanism for machine guns with a hydraulic counter-recoil-brake, wherein the recoil energy for effecting the weapon advance is stored and with a hydraulic braking piston equipped with throttle valves, comprising a cylinder having an end wall and connected with reciprocating parts of the weapon and receiving a hydraulic braking piston equipped with throttle valves and including a piston rod formed as a ram,

a housing having said cylinder disposed therein for relative longitudinal displacement and receiving said recoilmechanism,

forward and rearward resilient abutments supporting said cylinder on both sides and said housing adapted to be connected with immovable parts of said weapon,

additional abutment means effective upon said braking piston,

said additional abutment means for setting said piston forwardly relative to said cylinder during the return stroke of said cylinder, and

said piston rod eittending out from said end wall of said cylinder, being supportable during the forward stroke on said forward resilient abutment, before said cylinder itself having reached its initial position.

2. The recoil-mechanism, as set forth in claim 1, wherein said cylinder has a rearward end wall, and

said braking piston is supported by means of said additional abutment means which constitutes a spring operatively against said rearward end wall of said cylinder.

3. The recoil-mechanism, as set forth in claim 1, wherein said piston rod includes a rearward extending piston rod which is supported by said additional abutment means which constitutes a rigid abutment disposed in said housing of said recoil-mechanism.

4. The recoil-mechanism, as set forth in claim 1, wherein the forward resilient abutment comprises two shoulder bushings disposed in a joint holder with a spring tensioned between said two shoulder bushings and is insertable as an independent structural element into said housing of said recoil-mechanism. 5. The coil-mechanism, as set forth In claim 4, wherein said joint holder comprises a screw bolt, which is releasably and adjustably secured and is guided in an outer of said shoulder bushings for longitudinal displacement. 

1. A recoil-mechanism for machine guns with a hydraulic counterrecoil-brake, wherein the recoil energy for effecting the weapon advance is stored and with a hydraulic braking piston equipped with throttle valves, comprisiNg a cylinder having an end wall and connected with reciprocating parts of the weapon and receiving a hydraulic braking piston equipped with throttle valves and including a piston rod formed as a ram, a housing having said cylinder disposed therein for relative longitudinal displacement and receiving said recoil-mechanism, forward and rearward resilient abutments supporting said cylinder on both sides and said housing adapted to be connected with immovable parts of said weapon, additional abutment means effective upon said braking piston, said additional abutment means for setting said piston forwardly relative to said cylinder during the return stroke of said cylinder, and said piston rod extending out from said end wall of said cylinder, being supportable during the forward stroke on said forward resilient abutment, before said cylinder itself having reached its initial position.
 2. The recoil-mechanism, as set forth in claim 1, wherein said cylinder has a rearward end wall, and said braking piston is supported by means of said additional abutment means which constitutes a spring operatively against said rearward end wall of said cylinder.
 3. The recoil-mechanism, as set forth in claim 1, wherein said piston rod includes a rearward extending piston rod which is supported by said additional abutment means which constitutes a rigid abutment disposed in said housing of said recoil-mechanism.
 4. The recoil-mechanism, as set forth in claim 1, wherein the forward resilient abutment comprises two shoulder bushings disposed in a joint holder with a spring tensioned between said two shoulder bushings and is insertable as an independent structural element into said housing of said recoil-mechanism.
 5. The coil-mechanism, as set forth in claim 4, wherein said joint holder comprises a screw bolt, which is releasably and adjustably secured and is guided in an outer of said shoulder bushings for longitudinal displacement. 